More work towards hybrid support

* All packaging architecture dependent variables do now have a
  respective suffix and are set up for each configured packaging
  architecture, save for the kernel and boot loader variables, which
  are still only set up for the primary architecture.
  For convenience TARGET_PACKAGING_ARCH, TARGET_ARCH, TARGET_LIBSUPC++,
  and TARGET_LIBSTDC++ are set to the respective values for the primary
  packaging architecture by default.
* Introduce a set of MultiArch* rules to help with building targets for
  multiple packaging architectures. Generally the respective targets are
  (additionally) gristed with the packaging architecture. For libraries
  the additional grist is usually omitted for the primary architecture
  (e.g. libroot.so and <x86>libroot.so for x86_gcc2/x86 hybrid), so that
  Jamfiles for targets built only for the primary architecture don't
  need to be changed.
* Add multi-arch build support for all targets needed for the stage 1
  cross devel package as well as for libbe (untested).

build/jam/MainBuildRules

@@ -9,15 +9,10 @@ rule AddSharedObjectGlueCode
 	on $(1) {
 		platform = $(PLATFORM) ;
 		if $(platform) = haiku {
-			local stdLibs = libroot.so ;
-			local beginGlue ;
-			local endGlue ;
-			if $(2) = true {
-				beginGlue += $(HAIKU_EXECUTABLE_BEGIN_GLUE_CODE) ;
-				endGlue += $(HAIKU_EXECUTABLE_END_GLUE_CODE) ;
-			} else {
-				beginGlue += $(HAIKU_LIBRARY_BEGIN_GLUE_CODE) ;
-				endGlue += $(HAIKU_LIBRARY_END_GLUE_CODE) ;
+			local stdLibs = [ MultiArchDefaultGristFiles libroot.so ] ;
+			local type = EXECUTABLE ;
+			if $(2) != true {
+				type = LIBRARY ;
 
 				# special case for libroot: don't link it against itself
 				if $(DONT_LINK_AGAINST_LIBROOT) {
@@ -25,6 +20,11 @@ rule AddSharedObjectGlueCode
 				}
 			}
 
+			local beginGlue
+				= $(HAIKU_$(type)_BEGIN_GLUE_CODE_$(TARGET_PACKAGING_ARCH)) ;
+			local endGlue
+				= $(HAIKU_$(type)_END_GLUE_CODE_$(TARGET_PACKAGING_ARCH)) ;
+
 			LINK_BEGIN_GLUE on $(1) = $(beginGlue) ;
 			LINK_END_GLUE on $(1) = $(endGlue) ;
 
@@ -199,9 +199,9 @@ rule Ld
 			LINK on $(target) = $(HOST_LD) ;
 			LINKFLAGS on $(target) = $(HOST_LDFLAGS) $(LINKFLAGS) $(linkerFlags) ;
 		} else {
-			LINK on $(target) = $(TARGET_LD) ;
-			LINKFLAGS on $(target) = $(TARGET_LDFLAGS) $(LINKFLAGS)
-				$(linkerFlags) ;
+			LINK on $(target) = $(TARGET_LD_$(TARGET_PACKAGING_ARCH)) ;
+			LINKFLAGS on $(target) = $(TARGET_LDFLAGS_$(TARGET_PACKAGING_ARCH))
+				$(LINKFLAGS) $(linkerFlags) ;
 		}
 
 		NEEDLIBS on $(target) = $(NEEDLIBS) ;
@@ -265,8 +265,9 @@ rule CreateAsmStructOffsetsHeader header : source
 			}
 
 		} else {
-			sysHeaders += $(TARGET_HDRS) ;
-			defines += $(TARGET_DEFINES) ;
+			sysHeaders += $(TARGET_HDRS_$(TARGET_PACKAGING_ARCH)) ;
+			defines += $(TARGET_DEFINES_$(TARGET_PACKAGING_ARCH))
+				$(TARGET_DEFINES) ;
 		}
 
 		# optimization flags
@@ -299,18 +300,22 @@ rule CreateAsmStructOffsetsHeader header : source
 		} else {
 			# warning flags
 			if $(WARNINGS) != 0 {
-				flags += $(TARGET_WARNING_C++FLAGS) ;
+				flags += $(TARGET_WARNING_C++FLAGS_$(TARGET_PACKAGING_ARCH)) ;
 			}
 
 			# debug and other flags
-			flags += $(TARGET_C++FLAGS) $(TARGET_DEBUG_$(DEBUG)_C++FLAGS)
+			flags += $(TARGET_C++FLAGS_$(TARGET_PACKAGING_ARCH))
+				$(TARGET_DEBUG_$(DEBUG)_C++FLAGS_$(TARGET_PACKAGING_ARCH))
 				$(SUBDIRC++FLAGS) $(C++FLAGS) ;
 
-			C++ on $(header) = $(TARGET_C++) ;
+			C++ on $(header) = $(TARGET_C++_$(TARGET_PACKAGING_ARCH)) ;
 
-			includesSeparator = $(TARGET_INCLUDES_SEPARATOR) ;
-			localIncludesOption = $(TARGET_LOCAL_INCLUDES_OPTION) ;
-			systemIncludesOption = $(TARGET_SYSTEM_INCLUDES_OPTION) ;
+			includesSeparator
+				= $(TARGET_INCLUDES_SEPARATOR_$(TARGET_PACKAGING_ARCH)) ;
+			localIncludesOption
+				= $(TARGET_LOCAL_INCLUDES_OPTION_$(TARGET_PACKAGING_ARCH)) ;
+			systemIncludesOption
+				= $(TARGET_SYSTEM_INCLUDES_OPTION_$(TARGET_PACKAGING_ARCH)) ;
 		}
 	}
 
@@ -318,6 +323,7 @@ rule CreateAsmStructOffsetsHeader header : source
 	# for non-PODs. Since we're using the same compiler for the whole kernel and
 	# don't do virtual inheritence, that works well enough.
 	flags += -Wno-invalid-offsetof ;
+		# TODO: Rather get rid of the respective offsetof() instances.
 
 	# locate object, search for source, and set on target variables
 
@@ -366,8 +372,9 @@ rule MergeObjectFromObjects
 			LINK on $(1) = $(HOST_LD) ;
 			LINKFLAGS on $(target) = $(HOST_LDFLAGS) ;
 		} else {
-			LINK on $(1) = $(TARGET_LD) ;
-			LINKFLAGS on $(target) = $(TARGET_LDFLAGS) ;
+			LINK on $(1) = $(TARGET_LD_$(TARGET_PACKAGING_ARCH)) ;
+			LINKFLAGS on $(target)
+				= $(TARGET_LDFLAGS_$(TARGET_PACKAGING_ARCH)) ;
 		}
 	}
 
@@ -469,12 +476,12 @@ rule LinkAgainst
 
 	on $(target) {
 		# map libraries, if desired and target platform is Haiku
-		if $(PLATFORM) != host && $(mapLibs) = true
-				&& $(TARGET_LIBRARY_NAME_MAP) {
+		local map = $(TARGET_LIBRARY_NAME_MAP_$(TARGET_PACKAGING_ARCH)) ;
+		if $(PLATFORM) != host && $(mapLibs) = true && $(map) {
 			local mappedLibs ;
 
 			for i in $(libs) {
-				local mapped = $($(TARGET_LIBRARY_NAME_MAP)_$(i)) ;
+				local mapped = $($(map)_$(i)) ;
 				mapped ?= $(i) ;
 				mappedLibs += $(mapped) ;
 			}